Separation and enrichment of EGCG by molecularly imprinted solid-phase extraction technique

In order to separate and enrich (-)-epigallocatechin gallate (EGCG) by molecularly imprinted solid-phase extraction technique, the molecularly imprinted polymers (MIPs) were synthesized onto micron-sized silica gel particles by thermal polymerization method with EGCG as template molecule, γ-aminopropyl triethoxysilane as functional monomer and tetraethyl orthosilicate as coupling agent. The MIPs were characterized by Fourier transform infrared (FT-IR) spectroscopy, element analysis, scanning electron microscopy (SEM), and evaluated by static, kinetic solid-phase extraction experiments. The results show that using deionized water of pH 5 as adsorption solvent at temperature of 25°C, the adsorption quantity of MIPs for EGCG is 2.8 times than that of NIPs, and the adsorption is in accordance with Scatchard model. The adsorption equilibrium can be reached within 4 h, and the adsorption kinetics of EGCG onto the SMIPs can be described by pseudo-first-order adsorption model. The solid-phase extraction experiments of MIPs indicate that the adsorption capacity of EGCG on MIPs is 13, 26, 12, 9 and 11 times than those of its analogues of C, EGC, EC, ECG and GCG, respectively. The separation and enrichment of EGCG can be realized by MIPs solid-phase extraction technique.